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Monday, August 11, 2003
Feature

Be smart with your hard disk
Hitesh Bergal

RELIABILITY is a quality we seek in our daily lives. Disk drive manufacturers also aim at improving the reliability of their products with the sole purpose of achieving customer satisfaction. They take giant steps towards predicting reliability in disk drives, a step marked by the emergence of Self monitoring, Analysis and Reporting Technology (SMART). Computer users today have high expectations about data storage reliability. Many users do not even consider the possibility of losing data due to a hard disk failure. Even though continuous improvements in technology makes data loss uncommon, it is not impossible. Reliability prediction technology is a way to anticipate the failure of a disk drive with sufficient notice to allow a system, or user to back-up data prior to a driveís failure.

SMART is reliability prediction technology for both ATA/IDE and SCSI environments. Pioneered by Compaq, SMART is under continuous development by the top five disk drives manufacturers in the world ó Seagate Technology Inc., IBM, Conner Peripherals Inc. Western Digital Corporation and Quantum Corporation.

Evolution

In order to understand how SMART evolved, it is necessary to look at SMARTís roots that are based in technology developed by Compaq. IBMís reliability prediction technology is called Predictive Failure Analysis (PFA). PFA measures several attributes, including head flying height, to predict failures. The disk drive upon sensing degradation of an attribute, such as flying height, sends a notice to the host that a failure may occur. Upon receiving a notice, users can take steps to protect their data. Sometime ago, Compaq announced a breakthrough in diagnostic design called Intellisafe. This technology, developed in conjunction with Seagate, Quantum and Conner, monitors a range of attributes and sends threshold information to host software. The disk drive then decides if an alert is warranted and sends that message to the system, along with the attribute and threshold information. The attribute and threshold level implementation of Intellisafe varies with each disk drive vendor, but the interface, and the way in which status is sent to host, are consistent across all vendors. Compaq placed Intellisafe in the public domain by presenting their specification for the ATA/IDE environment, SFF-8035, to the small form factor committee in 1995. Features of SMART technology include a series of attributes, or diagnostics, chosen specifically for each individual drive model. Attributes individualism is important because architectures vary from model to model. Attributes and thresholds that detect failure for one model may not be functional for another model.

Specifications

SMART emerged for the ATA/IDE environment when SFF-8035 was placed public domain. The SMART system technology of attributes and thresholds is similar in ATA/IDE and SCSI environments, but the reporting of information differs. In ATA/IDE environment, software on the host interprets the alarm signal from the drive generated by the report status command of SMART. The host polls the drive on a regular basis to check the status of this command and if it signals imminent failure, sends an alarm to the end user or system administrator. This allows downtime to be scheduled by the system administrator to allow for the backup of data and replacement of the drive. This structure also allows for future enhancements, which might allow reporting of information other than drive conditions, such as thermal alarms, CD/DVD ROM, tape or other I/O reporting.

SMART on PC

In order to set the SMART status for your hard disk drive, enter the CMOS setup of your computer. Then open the advanced CMOS setup and enable the option SMART for hard disks, press Escape and then F10 key for quitting the setup by saving the changes.